Image encoding and recording apparatus

ABSTRACT

An image coding apparatus comprises:  
     a) first means for fixing or limiting quantity of code produced by compressively coding a given image data, independent of the image; and  
     b) second means for conducting valiable length compression of which quantity of code produced varies according to the image; and  
     selection means for selecting the first and second means.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an image encoding apparatus forcompression encoding of image signal and an image recording apparatusfor recording image signal.

[0003] 2. Related Background Art

[0004] Conventional image recording apparatus, for example still videocamera, is based for example on analog signal recording on floppy disksor recording of digital image data, compressed by fixed length encoding,in semiconductor memory cards. The fixed length encoding means acompression encoding in such a manner that the amount of compressedcodes of an image frame becomes equal to a predetermined value.

[0005] Such conventional image signal recording methods can guaranteethe number of images recordable per recording medium, because thecapacity thereof required for recording image data of an image frame ispredetermined.

[0006] However, for example in a digital still video camera employingimage data compression with a fixed length encoding method, the rate ofcompression can empirically be only increased to the order of 8bit/pixel, including the luminance and the color information, in orderto guarantee the quality of compressed image for various image data, forexample those involving fine patterns. Thus the fixed length encodingcannot achieve a sufficiently high compression rate. On the other hand,a variable length encoding method can achieve efficient compressionwhile guaranteeing sufficient image quality. The variable lengthencoding generates codes of variable length depending on the image, andempirically provides an encoding rate of 2-4 bit/pixel, including theluminance and color information and guaranteeing the image quality. Inthis case, however, it is not possible to guarantee the total number ofimages recordable per recording medium, because the total amount ofcodes varies according to the image. Also if the capacity of therecording medium is limited, the image may not be recordable on therecording medium.

[0007] Consequently, such variable length encoding method, if employedin a recording apparatus, results in a significant inconvenience as theuser is unable to recognize, in advance, the number of images stillrecordable on the recording medium.

[0008] As explained in the foregoing, a system employing fixed lengthencoding has been unable to guarantee the image quality, while a systememploying variable length encoding has been unable to guarantee thenumber of recordable images. Thus either system has been inconvenientfor the user.

SUMMARY OF THE INVENTION

[0009] In consideration of the foregoing an object of the presentinvention is to provide an image encoding method or apparatus, or animage recording method or apparatus, capable of individually orcollectively resolving the drawbacks mentioned above.

[0010] Another object of the present invention is to provide an imagerecording apparatus capable of presetting the stable recordingconditions prior to the actual recording operation.

[0011] Still another object of the present invention is to provide anapparatus allowing the operator to know, prior to a recording operation,whether such recording operation is possible or not.

[0012] Still another object of the present invention is to provide animage recording apparatus employing a variable length encoding methodand still convenient for use.

[0013] The above-mentioned objects can be attained, according to apreferred embodiment of the present invention, by an apparatus providedwith first means for effecting variable length encoding on signalsobtained by photoelectric conversion of an object image therebygenerating variable length code data; recording means for recording saidvariable length code data on a medium; and second means for convertingsaid object image to generate a value corresponding to the amount ofsaid variable length code data, prior to the recording by said recordingmeans.

[0014] Still another object of the present invention is to provide animage encoding method or apparatus which is convenient for use and stillallows efficient use of the recording capacity of the recording medium.

[0015] Still another object of the present invention is to provide anovel image recording apparatus having image taking capability.

[0016] Still other objects of the present invention, and the advantagesthereof, will become fully apparent from the following description ofthe embodiments thereof, to be taken in conjunction with the attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a block diagram of an embodiment of the presentinvention;

[0018]FIG. 2 is a timing chart showing the function of the apparatusshown in FIG. 1;

[0019]FIG. 3 is a flow chart of the control sequence of the apparatusshown in FIG. 1;

[0020]FIGS. 4 and 5 are flow charts showing details of parts of the flowchart shown in FIG. 3;

[0021] FIGS. 6-1 and 6-2 are flow charts of the control sequence ofanother embodiment of the present invention; and

[0022]FIGS. 7A and 7B are charts for explaining the embodimentcorresponding to FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023]FIG. 1 is a block diagram of an embodiment of the presentinvention. Other parts of the camera not directly related to the presentinvention, such as the diaphragm and the shutter, are naturally providedbut not shown. An optical image of an object, formed by a lens 1, isconverted into an electrical image signal by an image pickup device 2,such as a charge-coupled device (CCD), positioned behind said lens. Saiddevice 2 effects accumulation of charges corresponding to the opticalimage of the object and readout of image signal, in response to controlsignals given by a control unit 7. The obtained image signal isconverted into a digital signal by an A/D converter 3. Between the imagepickup device 2 and the A/D converter 3, there are provided means forregulating the image signal such as gamma correction, formation andseparation of color signals, white balance process etc. though suchmeans are not illustrated.

[0024] The digital image signal is stored in an image memory 4.

[0025] A compression encoding circuit 5 effects compression encoding onthe image data read from the image memory 4 and sends the obtained codesto a recording unit 6. The control unit 7 is so constructed as tocontrol the recording and reproducing for example with MS-DOS commandsthrough the recording unit 6. The compression is conducted by a variablelength encoding or a fixed length encoding, for example by DCTconversion of the image as will be explained later, followed by entropyencoding.

[0026] Also there is provided a function of counting the amount ofcompressed codes without the supply thereof to the recording unit 6. Forthis purpose there is provided a counting circuit 16 for counting theamount of compressed encoded data prior to the supply thereof to therecording unit 6.

[0027] The recording unit 6 is provided with a recording medium such asa semiconductor memory or a tape-shaped medium, is capable ofinformation exchange with the control unit, of recording or reading ofarbitrary digital data at an arbitrary physical address of the recordingmedium, and of counting the empty capacity of said recording medium.

[0028] The control unit 7 controls the entire apparatus by controllingthe units 2-6, and is also capable of controlling the image data filesin the recording medium, through the recording unit.

[0029] More specifically the control unit 7 correlates the fileinformation with the physical addresses on the recording medium, as in adisk operating system employed in a computer system, and is thereforecapable of controlling the mode of recording of files (compressed imagedata) on the recording medium, and also the empty capacity thereof. Ifthe compressed codes have to be stored in divided plural parts with alimited recording unit each, the control unit 7 causes the recordingunit 6 to record the compressed codes by designating the physicaladdress on the medium and the data length for each recording unit. Whenan image file is recorded in plural positions on the recording medium,the control unit 7 also records information indicating said positions,on the recording medium.

[0030] A man-machine interface (MMIF) 8 includes an operation member 9for actuating switches SW1, SW2 for shutter releasing and other switchesto be explained later, and display devices 10 including a display in theview finder, an external LCD display, a buzzer etc.

[0031] In an actual phototaking operation, the number of recordableimages is displayed as will be explained in the following, withreference to a flow chart shown in FIG. 3.

[0032] (1) At first the control unit 7 sends commands DIR, CHK, DSK tothe recording unit 6 to release the empty capacity therefrom (S1). Whena shutter release button is depressed by a half stroke (switch SW1 on)for a phototaking operation, the control unit effects focusing bydriving the lens 1, then activates the diaphragm and the shutter therebyexposing the image pickup device (S5), fetches the image information inthe memory (S7), and effects compression encoding (S9). The control unitcauses the counting circuit 16 to count the amount of codes of the imagedata, also causes the recording unit to count the empty capacity, andcalculates, from thus obtained data, the number of frames that can berecorded (S11). Said number is obtained for example by dividing theempty capacity with the amount of codes of image data. Thus calculatedvalue is informed to the user by a display device 10 provided in theview finder (S13). The display is continued while the switch SW1 isclosed (S15, S17). When the shutter releasing button is depressed deeperfor the phototaking operation, the sequence branches from the step S17to steps S19, S21 and S23 to effect similar operations as those in thesteps S5, S7 and S9, thereby fetching anew an image to be actuallyrecorded.

[0033] (2) When a continuous phototaking mode is not selected, thesequence branches from a step S25 to the step S3. On the other hand,when said mode is selected, the empty capacity of the recording mediumwill decrease with the phototaking operations, and the amount of codesof image data per frame may also vary. Thus, after the recording of thefirst frame in said mode, the empty capacity and the amount of imagecodes to be recorded next are counted after the recording of each frame(S23) and the decreasing number of recordable images is continuouslydisplayed in the view finder (S29).

[0034] Thus, in the present embodiment, if the continuous recording modeis selected and while the switch SW2 is kept closed, the images arefetched in the memory, encoded and stored in succession. In thisoperation, the number of recordable images is calculated from the amountof codes of the image recorded immediately before and the empty capacityof the recording medium, and the decreased number of recordable imagesis displayed, in the present embodiment, in succession in the viewfinder. However such display need not necessarily be made in the viewfinder.

[0035] The details of the steps S21, S23 in FIG. 3 are shown in FIG. 4.

[0036] The sequence shown in FIG. 4 is conducted after the step S23 inFIG. 3, namely storage of the image data in the memory 4.

[0037] Referring to FIG. 4, the image signal stored in the memory 4 isread and compression encoded in the encoding circuit 5, and thuscompression encoded data are counting circuit 16 (S41). Then the amountof the compressed codes is compared with the empty capacity of therecording medium in the recording unit 6 (S43), and, if there is anenough empty capacity, a gate 18 is so controlled as to read the imagesignal again from the memory 4, to effect the compression encoding andto send the data to the recording unit 6 for recording.

[0038] In this case the control unit 7 instructs the image memory toeffect the readout of the image data, the compression encoding circuit 5to release the compressed codes, the recording unit 6 to record thecompressed codes, and the gate 18 to open the gate. It also designatesthe physical address and the data length on the medium for eachrecording unit to the recording unit 6 thereby recording the compressedcodes. Unless a recording command is given by the control unit 7, therecording unit 6 does not request the data output from the compressionencoding circuit 5, so that the function of said circuit 5 and the imagememory 4 is interrupted. Thus the control unit 7 can achieve therecording operation through the control of the functions of thecompression encoding circuit 5 and the image memory 4, by designatingthe physical address and the data length on the recording medium foreach recording unit according to the filing format, to the recordingunit.

[0039] The recording operation is completed when all the compressedcodes are recorded.

[0040]FIG. 2 shows the communication protocol between the control unit 7and the recording unit 6.

[0041] In FIG. 2, there are shown a data output request signal D-Reqfrom the recording unit 6 to the control unit 7, a signal D-Ack suppliedfrom the control unit 7 to the recording unit 6 and indicating that thedata from the compression encoding circuit 5 to the recording unit 6 areeffective; and 8-bit parallel output data D0-D7 supplied from thecompression encoding circuit 5 to the recording unit 6.

[0042]FIG. 2 shows the output of data of one byte each, through theexchange of signals D-Req and D-Ack between the control unit 7 and therecording unit 6.

[0043] Referring to FIG. 2, the data receiver (namely recording unit 6)shifts the signal D-Req from the high level state to the low levelstate, thereby requesting the data transmitter (namely encoding circuit5) to release the data. Detecting the low level state of said signalD-Req, the data transmitter release the data on the data bus (D0-D7),and shifts the signal D-Ack from the high to the low level state whenthe values of said data are fixed.

[0044] The data receiver fetches the signals on the data bus when thesignal D-Ack is shifted to the low level state, and returns the signalD-Req to the high level state. The data transmitter terminates the dataoutput to the data bus when the signal D-Req is shifted to the highlevel state, and returns the signal D-Ack to the high level state.

[0045] The data transfer is thus conducted by matching the function ofthe transmitter and the receiver through the above-explained hand-shakecommunications of the signals Req and Ack. Consequently the compressionencoding circuit 5 need not generate the compressed codes with a fixedtransfer rate, and the eventual variation in the code length dependingon the image does not cause any inconvenience.

[0046] Now referring to FIG. 4 again, if the sequence proceeds from thestep S43 to a step S47, the control unit causes the display unit 10 ofthe man-machine interface 8 to display that the recording operation isnot possible because of an insufficient empty capacity of the recordingmedium, thereby requesting the user to select either one of thefollowing three options:

[0047] (1) to interrupt the recording operation;

[0048] (2) to exchange the recording medium; and

[0049] (3) to erase one of the image files in the currently mountedrecording medium.

[0050] For this purpose the control unit 7 executes the steps S49, S51and S53.

[0051] If the option (1) is selected by the user, all the functions areinterrupted from the step S49.

[0052] If the option (2) is selected by the user, namely if therecording unit 6 detects the replacement of the recording medium andinforms the control unit 7 of that effect, the sequence returns to thestep S43.

[0053] If the option (3) is selected by the user, the control unit 7displays the number of recorded images on the display unit 10 (S55), andrequests the user to enter the sequential number of the image to beerased. In response to the entry by the user of the number of the imageto be erased with the operation switches (S57), the control unit 7erases the corresponding image file (S59) and the sequence returns tothe step S43.

[0054] The replacement of the recording medium may be mechanicallydetected by the recording unit as disclosed in the Japanese Laid-openPatent Sho 61-182669. The control unit 7 can make access to theinformation on the presence of such replacement through the recordingunit 6.

[0055] The above-explained control shown in FIG. 4 can ensure imagerecording to the user, even with a compression method with codes ofvariable length, thereby proving a system of improved convenience of useand still capable of guaranteeing the image quality.

[0056] Now reference is made to FIG. 5 for explaining the method ofdisplaying the number of recordable images, executed in the steps S11,S13 in FIG. 3.

[0057] The control unit 7 releases a command for detecting the emptycapacity, thereby causing the recording unit 6 to count the emptycapacity of the recording medium (S61), and calculates the number ofimages recordable on the recording medium, from said empty capacity andthe pre-stored representative value of the compression rate of thevariable length encoding method (S63).

[0058] As an example, a variable length encoding method disclosed in theJapanese Laid-open Patent Sho 63-124680 provides a code length of 2bit/pixel in average or 4.5 bit/pixel at longest. Thus a step S65displays, on the display unit 10, a standard number of recordable imagescalculated from the average code length of 2 bit/pixel, and a minimumguaranteed number of recordable images calculated from 4.5 bit/pixel.Naturally it is possible to display only either of said numbers. Thedisplay device 10 is composed for example of a liquid crystal display(LCD) or light-emitting diodes (LED), and can provide display in theupper part of the apparatus and/or in the view finder.

[0059] The above-explained embodiment provides a digital image recordingapparatus employing variable length encoding, provided with means forcounting the empty capacity of the recording medium and capable ofstoring the representative amount of compressed codes in variable lengthencoding, thereby calculating the number of images recordable on therecording medium from said calculated empty capacity and saidrepresentative amount, and further provided with means for displayingthe calculated number of recordable images, thereby displaying astandard number and/or a minimum guaranteed number of images recordableon said recording medium.

[0060] Also in the above-explained embodiment, the empty capacity of therecording medium is detected not only in the step S1 in FIG. 3 but alsoin the steps S11, S13 of which details are shown in FIG. 5. Thus saidempty capacity can be confirmed not only when the switch SW1 is closedbut also in a continuous recording operation.

[0061] Also the present embodiment can improve the convenience of useand still can guarantee the image quality even with a variable lengthencoding method, since the amount of recorded images or the number ofimages recordable on the recording medium can be guaranteed and informedto the user.

[0062] Also in the present embodiment, the amount of encoded data iscalculated, prior to the recording operation by the recording unit 6, byactual variable length encoding of the image signal which is obtained byphotoelectric conversion of the object image and stored in the memory 4,but the present invention is not limited to such embodiment and saidamount of encoded data may be obtained without actual variable lengthencoding. Therefore the prediction of data amount from a simplifiedencoding is also included in the present invention.

[0063] Also in the present embodiment the data to be stored in therecording medium are in advance stored in the memory 4, and a signalindicating the amount of encoded data obtained by variable lengthencoding of the data stored in said memory 4 is generated by actualvariable length encoding of the image signal obtained by photoelectricconversion of the object image and stored in said memory 4. However thepresent invention is not limited to such embodiment, and the amount ofencoded data may be obtained without the actual variable lengthencoding. Therefore, a prediction of the data amount, for example by asimplified encoding is also included in the present invention.

[0064] Also the control unit 7 for executing the sequence shown in FIG.4 controls said memory 4 according to the, comparison of thus generatedsignal and said data amount.

[0065] As explained in the foregoing, the present embodiment controlsmeans for storing in advance the information to be stored in therecording medium, according to the comparison of the empty capacity ofsaid recording medium and the amount of encoded data to be recorded, andcan therefore continue the storage of said information in said storagemeans, if necessary.

[0066] Also the present embodiment allows to know in advance the numberof recordable images.

[0067] Also as explained in the foregoing, the present embodimentgenerates a value corresponding to the amount of variable length data byconversion of the object image prior to the recording operation by therecording unit, so that certain measures can be taken in advance if therecording operation is impossible due to an excessively large amount ofencoded data.

[0068] For obtaining fixed length codes and variable length codes in thepresent embodiment, there is already known an adaptive compressiontransformation (ADCT) method employing a dispersed cosine transformation(DCT) disclosed in “ISO/JTC1/SC2/WG8/N800”. Such ADCT method can controlthe compression rate by an encoding parameter F. As shown in FIG. 7, thecompression bit rate is a monotonously decreasing function of theparameter F. In FIG. 7, (a) and (b) show the relationship between thebit rate and F in different images. As will be understood from thesecharts, said relationship varies depending on the image but is alwaysdecreasing monotonously. It is therefore possible to obtained a desiredbit rate through several trials with regulation of the parameter F.

[0069] In the present embodiment, the compression encoding circuit 5 canselect variable length encoding or fixed length encoding, according tothe aforementioned encoding method. More specifically, the variablelength encoding is conducted with the encoding parameter F is fixed, andthe fixed length encoding is conducted when the parameter F is varied toobtain a target code amount.

[0070] Also the control unit 7 can know such selection through theman-machine interface 8.

[0071] When the user selects a recorded image number-preferential modeand depresses the shutter release button in said interface, the controlunit 7 controls the image pickup device 2, the A/D converter 3 and theimage memory 4, thereby storing the digital data of the object image insaid image memory 4.

[0072] Then the control unit 7 sets the parameter F of the compressionencoding circuit 5, and causes said circuit 5 to compress the image datain the image memory and to count the compressed codes. In this stagesaid circuit 5 does not send the compressed codes to the recording unitbut merely counts the amount of encoded data. This operation is repeatedseveral times with different values of the parameter F, until a desiredamount of encoded data is obtained.

[0073] When a value of F providing a desired amount of encoded data isobtained, the control unit 7 provides the compression encoding circuit 5with said value, and instructs the recording unit 6 to release thecompressed codes, thereby re-starting the compressing operation. Thenthe control unit 7 instructs the recording unit 6 to record thecompressed codes. Through the above-explained operations, the compressedcodes, with a fixed length for an image frame, are recorded by therecording unit.

[0074] In an image quality preferential mode, the control unit selects asufficiently small value for the parameter F to be set in the encodingcircuit 5, in order to avoid deterioration of the image quality. Thusthe value of F is fixed, and the initial operation of determining thevalue F in the recorded image number preferential mode is not conductedin this case. Then the control unit causes the compression encodingcircuit to compress the image data in the image memory for supply to therecording unit 6, and causes said recording unit 6 to record thusobtained compressed codes.

[0075] In the present embodiment, when the encoding method is switchedbetween the fixed length encoding and the variable length encoding, thenumber of recordable images and the continuous recording speed are alsovaried accordingly. More specifically, in the fixed length encoding, thenumber of recordable images can be exactly calculated by dividing theempty capacity of the recording medium with the amount of codes, sincethe latter is fixed. However, said number cannot be exactly determinedin the variable length encoding. Also the variable length encoding,involving repeated process of plural times, required a longer timebefore recording than in the fixed length encoding, so that theselectable continuous recording speed becomes lower. These factsinfluence the displays on the camera and the setting of the continuousrecording speed.

[0076] In the present embodiment, the control unit 7 in the variablelength encoding mode determines the number of recordable images bydividing the empty capacity of the recording medium with the standard ormaximum code amount and displays said number. In the fixed lengthencoding mode, it decreases the upper limit of the selectable continuousrecording speed.

[0077]FIG. 6 is a flow chart for the above-explained procedures. Atfirst, when the power supply is turned on (S1), for example the fixedlength encoding mode is selected, and the minimum continuous recordingspeed is selected (S3).

[0078] The change of the fixed/variable length encoding mode isconducted by the user at a terminal S. Also if an instruction is givenfor varying the continuous recording speed, a corresponding procedure isconducted.

[0079] In case of such change, the sequence proceeds to a step S5. Incase of the fixed length mode, the empty capacity of the recordingmedium is divided with the code amount, and the obtained number ofrecordable images is displayed, and the continuous recording speed isselected at the upper limit selectable in the fixed length mode (S7). Incase of the variable length mode, said empty capacity is divided withthe standard or maximum code amount and the obtained number ofrecordable image displayed (S9). Also the continuous recording speed isselected at the upper limit selectable in the variable length encodingmode (S11).

[0080] Then in a step S20, if the current set value of the continuousrecording speed exceeds the selectable range of the continuous recordingspeed, said value is set at the upper limit of said selectable range(S22). Then the continuous recording speed is displayed (S24) and thesequence returns to the terminal S.

[0081] Also if an instruction is given to vary the continuous recordingspeed at S2, a step S30 discriminates whether the user has instructed toincrease the continuous recording speed by a unit by depressing anoperation button, and, if instructe, the sequence proceeds to a step S33to increase the currently set value of said speed by a unit. Then thusincreased speed is compared with the selectable range of the recordingspeed (S35), and if the former exceeds said range, the continuousrecording speed is reset to the minimum speed (S37). Then the set valueof the continuous recording speed is displayed (S39) and the sequencereturns to S.

[0082] As explained in the foregoing, the present embodiment improvesthe convenience of use, by the presence of means for allowing the userto select the fixed length encoding mode or the variable length encodingmode, thereby giving preference to the image quality or to the number ofrecordable images.

[0083] Also in the fixed length encoding mode of the present embodiment,there can be selected a high continuous recording speed, because thetime required for the encoding operation is fixed.

[0084] Also the compression encoding can be securely conducted becausethe upper limit of the continuous recording speed is automaticallymodified according to whether the compression encoding is conducted witha fixed length or a variable length.

[0085] The variable length compression encoding in the presentembodiment may be conducted in other various encoding methods. Forexample there may be employed an entropy encoding on the DCT encodeddata. There may be employed any encoding method as long as fixed lengthcompression encoding and variable length compression encoding can beswitched, so that both encodings need not be conducted by a same method.

[0086] In the present embodiment the recording unit 6 is composed of adata memory device controlled by an MS-DOS system, but there may also beemployed other media, such as a semiconductor memory or a tape-shapedmedium.

[0087] If the recording medium is composed of a floppy disk of verticalrecording type, a capacity of 5 M Bytes can be sufficiently providedwith a diameter of 2 inches. In such case the present embodiment canguarantee the recording of 55 television field images at standard or 22images at minimum.

[0088] In the present embodiment, the control unit 7 sends the commandsDIR, CHK, DKS to the recording unit 6 for obtaining the information onthe empty capacity of the memory means, but the control unit 7 directlydetect the unrecorded area of the memory means, namely an unrecordedarea for example on a tape.

[0089] Though the foregoing embodiment has been limited to so-calledstill video apparatus for recording still images on a recording medium,the present invention is not limited to such embodiment and is likewiseapplicable to a facsimile apparatus, an electronic image file or thelike.

1. An image coding apparatus comprising: a) first means for fixing orlimiting quantity of code produced by compressively coding a given imagedata, independent of the image; and b) second means for conductingvaliable length compression of which quantity of code produced variesaccording to the image; and selection means for selecting the first andsecond means.
 2. An image coding apparatus according to claim 1, whereinboth of said first and second means compress the image data of imagedata for one frame.
 3. An image coding apparatus according to claim 1,wherein said image data is multi-value image data.
 4. An image codingapparatus according to claim 1, wherein said image data is binary imagedata.
 5. An image coding apparatus according to claim 1, wherein saidfirst means performs DCT transformation coding.
 6. An image codingapparatus according to claim 1, wherein said selection means selects oneof said first and second means, according to an operator's instruction.7. An image coding apparatus according to claim 1, further comprisinggeneration means for generating the image data.
 8. An image codingapparatus according to claim 7, wherein said generation means is one fortransforming a symmetrical image into the image data.
 9. An image codingapparatus according to claim 1, wherein said selection means selectssaid first means when the operator's instruction is given.
 10. An imagerecording apparatus comprising: a) first means for transforming asymmetrical image into an image signal, and performing variable lengthcoding to produce a variable length coded data; b) recording means forrecording the variable length coded data on a medium; and c) secondmeans for transforming the symmetrical image to produce a valueaccording to a quantity of the valiable length coded data, prior to therecording by said recording means.
 11. An image recording apparatusaccording to claim 10, wherein said first means comprises generationmeans for photoelectrically converting the symmetrical image to producethe image signal; and transforming means for transforming the imagesignal produced by said generation means into a variable length code.12. An image recording apparatus according to claim 10, wherein saidmedium is a semiconductor memory.
 13. An image recording apparatusaccording to claim 10, wherein said medium is a disk memory.
 14. Animage recording apparatus according to claim 10, further comprisingcontrol means for controlling said apparatus according to a valuerelating to a quantity of the variable length coded data produced bysaid second means.
 15. An image recording apparatus according to claim14, wherein said controlling means controls said recording means basedon a value according to the quantity of data.
 16. An image recordingapparatus according to claim 10, further comprising generation means forgenerating an information indicating data quantity capable of beingrecorded in the medium, and third means for generating data of number offrames capable of being recorded in said medium, based on a valuerelating to quantity of data capable of being recorded in said mediumand to the coding data.
 17. An image recording apparatus for variablelength coding comprising: first means for generating an informationrelating to capacity of recording of a memory means; and second meansfor generating an information concerned with number of frames capable ofbeing recorded in said memory means based on the information from saidgeneration means and on a representative value of code quantitysubjected to variable length coding.
 18. An image recording apparatusaccording to claim 17, further comprising a display means for displayingaccording to the information generated by said second means.
 19. Animage recording apparatus according to claim 18, wherein said displaymeans display, a number of frames capable of being recorded.
 20. Animage recording apparatus according to claim 17, further comprisingthird means for generating an image data to be subjected to the variablelength coding.
 21. An image recording apparatus according to claim 20,wherein said third means is means for photoelectrically converting thesymmetrical image.
 22. An image recording apparatus according to claim21, wherein said representative value is a standard for variable lengthcoding.
 23. A recording apparatus comprising: a) generation means forgenerating an information concerned with a capacity of recording of arecording means; b) maintaining means for provisionally maintaining datato be stored in the memory means; c) generation means for generatingsignal indicating data quantity in case of a variable length coding ofdata maintained in said maintaining means; and d) control means forcontrolling said maintaining means based on a comparison between theinformation generated by said generation means and said data quantity.24. A recording apparatus according to claim 23, wherein said controlmeans make said maintaining means continuously maintain the data to bestored in said maintaining means when the data quantity is greater thanthe capacity of storing.
 25. A recording apparatus according to claim23, wherein said image data is an image data.
 26. A recording apparatusaccording to claim 25, wherein said image data is a multi-value imagedata.
 27. A recording apparatus further comprising: an image datageneration means for generating said image data.
 28. A recordingapparatus according to claim 27, wherein said image data generationmeans generates data photoelectrically converted from the symmetricalimage.